Electrode for electrolytic conversion cells including passage means in the electrode for electrolyte flow through the electrode

ABSTRACT

AN ELECRODE EMPLOYED IN AN ELECTROLYTIC CELL IS PROVIDED WITH AT LEAST ONE PASSAGEWAY EXTENDING THERETHROUGH, PREFERABLY IN A GENERALLY VERTICAL DIRECTION. ELECTROLYTE CIRCULATES THROUGH SAID PASSAGEWAY AND COOLS SAID ELECTRODE. IF DESIRED, CIRCULATION OF SAID ELECTROLYTE CAN   BE ENHANCED BY INTRODUCING AN INERT GAS INTO SAID PASSAGEWAY.

Nov. 13, 1973 K. MILLS 3,772,201

ELECTRQDE FOR ELECTROLYTIC CONVERSION CELLS INCLUDING PASSAGE MEANS INTHE ELECTRODE FOR ELECTROLY TE FLOW THROUGH THE ELECTRODE Original FiledMarch 2, 1970 3- Sheets-Sheet 1 I8 12 -E\r n v F/G. 3

o INVENTOR. v K.I MILLS d -L Y My W6 ATTORNEYS Nov. 13, 1973 OriginalFiled March 2, 1970 FEED BUS

52 4 PRODUCT SEPARATION MILLS 3.772201 K. L. ELECTRODE FOR ELECTROLYTICCONVERSION CELLS INCLUDING PASSAGE MEANS IN THE ELECTRODE FORELECTROLYTE FLOW THROUGH THE ELECTRODE I 3 Sheets-Sheet 2 MAKE-UP O G OO O O O O LU Q 0 E I LU 3 g z j l E 0 Lu 0 0: O '5 .i E INVENTOR. UJ K.L. MILLS d ATTORNEYS 1973 K. L. MILLS 3,772,201

ELECTRODE FOR ELECTROLYTIC CONVERSlON CELLS INCLUDING PASSAGE MEANS INTHE ELECTRODE FOR ELE'CTROLYTE FLOW THROUGH THE ELECTRODE r p I OriginalFiled March 2, 1970 FIG. 6a

v INVENTOR.

K.L. MILLS ATTORNEYS 3 Sheets-Sheet 3 I United States Patent 01 :"ficeUS. Cl- 204-277 13 Claims ABSTRACT OF THE DISCLOSURE An electrodeemployed in an electrolytic cell is provided with at least onepassageway extending therethrough, preferably in a generally verticaldirection. Electrolyte circulates through said passageway and cools saidelectrode. If desired, circulation of said electrolyte can be enhancedby introducing an inert gas into said passageway.

This application is a division of my copending application Ser. No.15,389, filed Mar. 2, 1970, now Pat. No. 3,663,380, issued May 16, 1972.

This invention relates to electrodes employed in electrolytic conversionprocesses.

Generally speaking, the utilization of an electrode in anelectrochemical conversion process involves immersing the electrode inan electrolyte and passing an electric current from one electrodeelement through said electrolyte to an oppositely charged electrodeelement. The electrochemical conversion, particularly when practiced ona commercial scale, is accompanied by the generation of considerableheat. Provision can be made for dissipation of said heat by providingmeans for cooling the electrolyte, either externally or internally ofthe cell.

However, the heat generated in the electrochemical conversion process isusually concentrated at one of the electrodes. This usually means thatthe electrode temperature is higher than the electrolyte temperature,particularly the temperature of the internal portion of the electrode.This has a number of disadvantages and creates problems in operation ofthe cell and the process. For example, excessive heating can cause theelectrode to be subject to intense hot spots which shorten the life ofthe electrode. When the surface(s) of the electrode is the point(s) atwhich a chemical reaction is occurring, the selectivity and efiiciencyof the reaction can be adversely affected. This can be particularly truewhen the reaction is occurring within the confines of the electrode,e.g., within the pores of a porous electrode. When the electrode isbeing employed as an anode, the increased temperature thereof cancontribute to the occurrence of anode effect.

The present invention provides a solution to the above problems. I havenow discovered that the temperature of an electrode in anelectrochemical conversion process can be maintained, and/or controlled,at desirable levels by providing said electrode with at least onepassageway which extends therethrough, preferably in a generallyvertical direction. Circulation of electrolyte through said passagewaywill then provide temperature control for the electrode, particularlythe internal portion thereof, with the result that the temperature ofthe electrode can be maintained more nearly uniform throughout itsstructure. I have also discovered that, if desired, the circulation ofthe electrolyte through said passageway can be enhanced by introducingan inert gas into said passageway.

An object of this invention is to provide an improved electrodestructure. Another object of this invention is 3,772,201 Patented Nov.13, 1973 to provide an improved electrode structure which is providedwith internal cooling means. Another object of this invention is toprovide an improved electrochemical conversion apparatus. Another objectof this invention is to provide an improved electrochemical conversionapparatus wherein means are provided for introducing an inert gas into atemperature adjusting passageway which extends through an electrodeemployed in an electrolytic cell. Another object of this invention is toprovide an electrochemical conversion process wherein the temperature ofthe electrode(s) employed therein can be maintained at substantially thesame temperature as the surrounding electrolyte. Other aspects, objects,and advantages of the invention will be apparent to those skilled in theart in view of this disclosure.

Thus, according to the invention, there is provided an electrodestructure comprising: an electrode element; an electrically conductivecurrent collector mounted in said electrode element; and at least onepassageway extending through said electrode element in a generallyvertical direction.

Further according to the invention, there is provided electrochemicalconversion apparatus comprising, in combination: an electrolytic cell; abody of electrolyte disposed in said cell; an electrode disposed in saidelectrolyte, said electrode having a passageway extending therethroughin a generally vertical direction; and means in communication with saidpassageway for introducing an inert gas into said passageway.

According to the invention now being claimed in said copendingapplication, there is provided in a process for the electrochemicalconversion of a feedstock at an electrode disposed in an electrolyte inan electrolytic cell, wherein said feedstock is subjected to contactwith said electrode and at least partially converted, and wherein saidelectrode in service attains a temperature different from thetemperature of said electrolyte, the improvement comprising: providingsaid electrode with at least one passageway extending generallyvertically therethrough, said passageway being in communication at atleast one end thereof with said electrolyte; and permitting saidelectrolyte to circulate through said passageway and cool saidelectrode.

In one preferred embodiment of said process, an inert gas is introducedinto the lower end of said passageway so as to increase the circulationof said electrolyte therethrough.

Electrodes are commonly fabricated from a wide variety of materials. Theinvention is applicable to and can be employed with electrodes made ofany material suitable for the process in which the electrode isemployed. One of the most advantageous applications of the invention isin electrodes fabricated from materials having a relatively poor heatconductivity. Such materials include ceramics and other porous materialshaving poor thermal conductivity which can be rendered electricallyconductive by impregnation and/ or coating with materials such asmetallic nickel, platinum, etc., which may or may not be catalytic; andvarious carbons including, for example, graphite, porous carbon, andnonporous carbon. Said carbons can also be impregnated and/or coated asdescribed, if desired. The carbons are preferred and most often used.

The inert gas employed in the practice of the'invention can be any gaswhich is inert, or essentially inert, with respect to the electrolyteused in the cell, the feedstock, and the products produced in the cell.Examples of suitable inert gases include the commonly known inert gasessuch as helium, argon, krypton, xenon, nitrogen, etc. Nitrogen, becauseof its ready availability, is a preferred gas. Frequency, a gas producedin the electrochemical conversion process can be employed as the inertgas. When such gases produced in the process are available, theyrepresent a preferred gas for use in the practice of the invention. Forexample, in the electrochemical fluorination of fluorinatable organiccompounds using an electrolyte comprising hydrogen fluoride, someperhalogenated compounds are produced in the process. Saidperhalogenated compounds are inert in the process and can be used in thepractice of the invention to enhance circulation of the electrolytethrough the passageway(s) provided in the anode. Hydrogen is produced atthe cathode in such fluorination processes and can be used in thepractice of the invention in some instances such as where thepassageways are provided in the dense core of the anode as discussedhereinafter. In such instances where no reaction is occurring in thedense core of the anode the hydrogen can, for practical purposes, beconsidered essentially inert.

The invention is applicable to electrode when employed as either theanode or the cathode in electrochemical conversion processes whereinheat liberated in the cell is concentrated at the anode and/or thecathode. One process in which the invention is particularly useful is inthe electrochemical fluorination processes employing an anode comprisingporous carbon and an electrolyte comprising essentially anhydrous liquidhydrogen fluoride. Thus, for purposes of illustration, and not by way oflimitation, the invention, in some instances, will be further describedherein with particular reference to an electrochemical fluorinationprocess employing an anode comprising porous carbon. Further details ofa presently preferred electrochemical conversion process in which theelectrodes of the invention can be employed as anodes can be found incopending application Ser. No. 683,089, filed Nov. 2, 1967, by H. M. Foxand F. N. Ruehlen, now Pat. 3,511,760. See also U.S. Pats. 3,461,049 and3,461,050, issued Aug. 12, 1969, to W. V. Childs.

FIG. 1 is a plan view of an electrode structure in accordance with theinvention.

FIG. 2 is a view diagrammatically illustrating the electrode of FIG. 1(in cross section along the line 2-2 of FIG. 1) employed in anelectrolytic cell in accordance with the invention.

FIG. 3 is a plan view of another electrode structure in accordance withthe invention.

FIG. 4 is a view diagrammatically illustrating the electrode of FIG. 3(in cross section along the line 44 of FIG. 3) employed in a cathodechamber of an electrolytic cell.

FIG. 5 is a diagrammatic illustration, partly in cross section,illustrating another electrode of the invention, said electrode beingemployed in a combination of apparatus in accordance with the invention.

FIG. 6 is a diagrammatic illustration, partly in cross section along theline 66 of FIG. 6a, of another electrode structure in accordance withthe invention.

FIG. 6a is a bottom view of the electrode structure of FIG. 6.

Referring now to the drawings, wherein like reference numerals areemployed to denote like elements, the invention will be more fullydescribed. In FIG. 1 and FIG. 2 there is illustrated an electrodestructure comprising an electrode element 10 having an electricallyconductive current collector 12 mounted therein. Electrode element 10can be made of any suitable material depending upon the process in whichit is being used, e.g., graphite, porous carbon, nonporous carbon, etc.At least one passageway 14 extends generally vertically through saidelectrode element. Preferably, a plurality of said passageways 14 areprovided and are uniformly spaced or distributed in the electrodeelement. As here illustrated, said electrode element 10 is beingemployed as an anode in an electrolytic cell 16, the case of which isbeing employed as the cathode. Preferably, the electrolyte level 18 willbe about even with or slightly above the top of the electrode element10.

In the operation of the apparatus illustrated in FIG. 2 the feedstock tobe converted can be dissolved in the electrolyte (as in some types ofelectrochemical fluorination processes) and thus brought into contactwith the surface of the anode at which the reaction takes place. Inoperation, heat will usually be liberated and concentrated at the anode.Means not shown, such as a cooling coil through which a coolant can becirculated, can be disposed in the elcetrolyte for dissipating saidheat. In some processes, such as electrochemical fluorination, hydrogenwill be liberated at the cathode, similarly as illustrated in FIG. 2.The heat generated in the cell, and usually concentrated at the anodewhere the principal reaction is occurring, will create a thermal siphon.When the space 15 between the anode and the cathode is relatively large,the gas lift effect of said liberated hydrogen, in the large bulk ofelectrolyte, will be minimized and the thermal siphon effect willprevail. Thus, in the cell illustrated, electrolyte will flow upwardlythrough said passageways 14 and downwardly around the electrode elementas indicated by the arrows. By providing said passageways 14 andpermitting the electrolyte to circulate therethrough, the internalregions of electrode element 10 can be cooled and maintained more nearlyat the same temperature as the electrolyte. If desired, circulation ofsaid electrolyte through passageway 14 can be enhanced by theintroduction of an inert gas through conduits 20 delivered thereto fromconduit 22 which is connected to any suitable source of inert gas. Saidinert gas will serve to further lessen the density of the electrolyte inpassageway(s) 14 and cause the circulation of the electrolyte to beenhanced.

Referring now to FIGS. 3 and 4, there is illustrated another electrodestructure in accordance with the invention. Said electrode structure isa composite structure. Composite electrode structures comprising aporous outer section and a less porous or more dense central sectionhave been found very useful in electrochemical conversion processes. Theporous section provides a location for carrying out the conversion orreaction. The less porous or more dense section provides a location forthe current collector or connection to the electric current. In onepresently preferred embodiment of the invention the electrode iscomprised of a porous outer section 24 which comprises a porous carbon,is generally cylindrical in shape, and is hollow. A core section 26comprising a dense, essentially impervious carbon has the general shapeof a generally cylindrical rod and is disposed within said outer section24. At least one passageway 14 extends generally vertically through saidcore section 26. A current collector 12 is mounted in said core section26. Said outer section 24 extends at one end thereof beyond one end ofsaid core section 26. The bottom surface of said core section 26together with the inner surfaces of said extended portion of said outersection 24 define a cavity 25 in the lower portion of the electrode.Said cavity is provided for the introduction of a feedstock by means ofconduit 28 into the pores of said outer section 24. A hollow conduct 30is secured to the lower end of and extends each of said passageways 14through said cavity.

As illustrated in FIG. 4, the electrode structure is being employed asan anode and is positioned in a generally cylindrical cathode chamber inan electrolytic cell provided with a plurality of such cathode chambers32. Said cathode chambers 32 are open at both ends and comprise thetubes in a heat exchange element wherein coolant is circulated on thecell or outer side of the cathode chambers 32. Said cathode chambers arein communication at both ends thereof with a body of electrolyte, thetop level of whlch is indicated at 18. Electrolytic cells constructed inthis general manner are illustrated in U.S. Pat. 3,404,- 083, issuedOct. 1, 1968, in the name of M. S. Kircher. Such cells are usuallyprovided with a plurality of empty chambers 32 which do not contain ananode and which serve as downcomers for the circulating electrolyte.However, by proper sizing of the annular space 34 relative to theavailable cross section in the passageway(s) 14 provided in core section26 of the electrode, the gas lift elfect of the hydrogen liberated atthe cathode can be caused to prevail over the thermal siphon effect andthe electrolyte, instead of circulating upwardly through saidpassageways 14 as in FIG. 2, can be caused to circulate upwardly throughannular space 34 and downwardly through said passageways 14, as shown bythe arrows in FIG. 4. Thus, the invention not only provides theadvantage of internal cooling of the electrode structure, but can alsoprovide the advantage of conserving cell space and structure by theelimination of special downcomer tubes. The method of operationillustrated in FIG. 4 is one presently preferred method of operating inaccordance with the invention. If desired, additional gas can beintroduced into annular space 34 (similarly as in FIGS. 2 and 5) toenhance the gas lift effect of the liberated hydrogen.

Referring to FIG. 5, there is illustrated an electrochemical conversionapparatus which comprises, in combination, an electrolytic cell 36having a body of electrolyte disposed therein. An electrode structure38, similar to the electrode structure illustrated in FIG. 4, isdisposed in said electrolyte. The current colector 12' comprises ahollow conduit through which a feedstock to be converted can beintroduced via conduit 40 into thecavity 25 in the lower portion of theelectrode. If desired, the current collector 12' can be a solid rod-likecurrent collector as in FIGS. 2 and 4. In this instance, the feedstockto be converted would be introduced into the cavity 25 in a mannersimilar to that illustrated in FIG. 4. A suitable lead wire 42 isconnected to current collector 12 in any suitable manner and serves toconnect the anode to the anode bus of the current supply. A circularcathode 44, which can be a screen formed of a suitable metal such asstainless steel depending upon the nature of the electrolyte, surroundssaid anode and is connected to the cathode bus of the current supply bya suitable lead 'wire 46. A cool1ng coil 48, having coolant inlet andoutlet conduits connected thereto as illustrated, is provided forremoving heat from the electrolyte and thus dissipating the heatgenerated in the process.

In the operation of the cell arrangement of FIG. 5 a feedstock isintroduced into cavity 25 via conduit current collector 12', enters thepores of porous carbon section 24 from said cavity 25, travels upwardthrough the pores of said porous carbon, and exits from the upper endthereof and passes into the space within the cell above electrolytelevel 18. During passage through said anode at least a portion of thefeedstock is electrochemically converted. Converslon products, togetherwith remaining unconverted feedstock, and possibly some electrolytevapors, are withdrawn via conduit 52 from the space above theelectrolyte within cell 36 and passed to product separation means 54.Said product separation means can comprise any suitable means foreffecting a separation of the materials in the cell efiiuent stream.

In a process for the electrochemical fiuorination of a fluorinatableorganic compound using an essentially anhydrous liquid hydrogen fluorideelectrolyte, hydrogen will be produced at the cathode. Said hydrogen canbe withdrawn from separation means 54 via conduit 56 and at least aportion thereof passed via conduit 58 for introduction via conduits 60into the bottom of passageways 14 to enhance the circulation ofelectrolyte through said passageway 14. Perhalogenated products of theprocess can be withdrawn via conduit 55 and used to enhance saidelectrolyte circulation. If desired, the amount of said hydrogen, orother inert gas introduced via conduit 60*, can be controlled inaccordance with the temperature of electrode element 38. A temperaturesensing means 62 is disposed in said electrode structure for measuringthe temperature within the electrode. Said temperature sensing means isoperatively connected in known manner to temperature controller 64which, in turn, is operatively connected to flow control valve 66disposed in conduit 58.

If desired, a suitable inert gas from any suitable source can beintroduced via conduit 68 instead of using hydrogen or other inert gasfrom conduit 56. Any HF electrolyte recovered in product separationmeans 54 can be returned to the cell via conduits 70 and 72. Make-upelectrolyte can be supplied as needed.

The electrode structure illustrated in FIG. 6 is generally rectangularin shape. Said electrode comprises a first rectangular-shaped outersection 74, a core section 76, and a second rectangular-shaped outersection 78. A hollow conduit current collector 12 is mounted in saidcore section, similarly as in FIG. 5, by a friction fit. Said firstouter section 74 and said second outer section 78 extend below said coresection 76 on the sides of the electrode as indicated in FIG. 6. Saidcore section 76 extends downwardly at the ends of the electrode to thesame level as the ends of said first and second outer sections, as shownin FIG. 6a to form cavity 25'. A pair of clamp means 80 comprising aband of metal and a bolt 82 are provided for securing said electrodesections together. Said FIG. 6a is a bottom view of the electrode ofFIG. 6, and shows the cavity 25' formed in the bottom of the electrode.A reactive feedstock can be introduced into said cavity for introductioninto the pores of the first and second outer FIG. 5.

In the sections of the composite electrodes of the invention whichcomprise porous carbon, the average pore diameter can be generally inthe range of 1 to microns, preferably between 40 and 140, and still morepreferably between 50 and 120, microns. These values depend somewhat onthe depth of immersion of the electrode, with deeper immersionsrequiring somewhat smaller pores within the above ranges. Generally, thepremeability of such porous carbons will be in the range of 0.5 to 75darcys. In general, the total porosity can be in the range of about 15to about 60 percent. The less porous or more dense core or centralsections of the electrodes of the invention can have a pore size withinthe range of about 0.01 to 35, preferably 0.1 to 10, microns averagediameter with no significant amount of pores having a diameter exceeding70 microns.

In the electrodes of the invention the passageway(s) 14 extendingtherethrough have been illustrated as extending in a vertical direction.This, in most instances, is preferred. However, it is within the scopeof the invention for said passageways to extend in directions other thanstrictly vertical so long as the general direction is upward orgenerally vertical so as to utilize the thermal siphon and/or gas lifteffect. For example, any of the electrodes illustrated in FIGS. 2, 4, 5,and 6 could be provided with spiral passageways. As another example, thepassageways 14 in FIGS. 4, 5, and 6 could pass through the outersections of the electrode in a slanting direction to enter the coresection and then either spiral upward or extend generally verticallyupward. Said passageways in passing through the outer sections of theelectrode would be sealed therefrom.

A number of advantages are realized in the practice of the invention.The passageways 14 make it possible to control the temperature of theelectrode to be more nearly the same as the temperature of theelectrolyte. Generally, this will involve cooling of the electrode.However, it is within the scope of the invention to increase thetemperature of the electrode by circulating a Warmer electrolytetherethrough. The protection of the electrodesfrom excessive variationsin temperature will extend the life of the electrode, and will also makeit possible to control and/or preserve the selectivity and efficiency ofthe reactions being carried out at the electrodes. In situations wherethe reaction occurring at the electrode is temperature dependent, themore uniform electrode temperatures made possible by the invention willreduce the formation of undesirable by-products. Also, as discussed inconnection with FIG. 4, the electrodes of the invention make possiblemore efiicient cell construction.

While the electrodes of the invention have been illustrated as anodes,and in some instances have been described with particular reference toelectrochemical fluorination processes, the invention is not so limited.The electrodes of the invention can be employed as either anodes orcathodes in any convenient cell configuration or electrode arrangement.The electrodes of the invention can be employed in a wide variety ofelectrochemical conversion processes. Some examples of such processesare electrochemical halogenation, electrochemical cyanation, andcathodic conversion such as the reduction of alcohols to hydrocarbons orthe reduction of acids to alcohols.

The following calculated example will serve to further illustrate theinvention.

EXAMPLE An electrochemical fluorination cell comprising four 5.5 inchI.D. cathode chambers 32, such as illustrated in FIG. 4, is employed inthis illustrative embodiment. Each of said cathode chambers has a 4 inchO.D. anode disposed therein, similarly as illustrated in FIG. 4. Saidfour cathode chambers are uniformly spaced around a centrally disposedempty downcomer tube having a 5.5 inch I.D. Four small downcomer tubesare also provided and are uniformly disposed among said cathodechambers. The cell contains an essentially anhydrous KF-ZHF electrolyte.In operation 250 amperes current is applied to each anode.

In Run 1, wherein the anodes are not provided with passageways 14extending therethrough, circulation of electrolyte is upward throughannular space 34 and then downward through said downcomers. Saidcirculation is caused primarily by the gas lift effect created by thehydrogen liberated along the wall surface of cathode chamber 32. In thisoperation in accordance with the prior art, and at an electrolytetemperature of 100 C., the temperature of the interior of the anodes inthe top portion and bottom portion is about 110 C., and in the middleportion is about 140 to 150 C.

In Run 2, each of the anodes disposed in cathode chambers 32 is providedwith eleven uniformly spaced 0.25 inch diameter passageways 14 extendingvertically through the core section 26 of the anode. Said largedowncomer tube and said four downcomer tubes are plugged to preventcirculation therethrough. Thus, in this run circulation of theelectrolyte is upward through annular space 34 and then downward throughsaid passageways in the anodes. In this operation in accordance with theinvention, at an electrolyte temperature of 100 C., and all otherconditions essentially the same as in Run 1, the temperature of theinterior of the anodes in the top portion and bottom portion is about110 C., but in the middle portion is only about 120 to 130 C.

While certain embodiments of the invention have been described forillustrative purposes, the invention is not limited thereto. Variousother modifications or embodiments of the invention will be apparent tothose skilled in the art in view of this disclosure. Such modificationsor embodiments are within the spirit and scope of the disclosure.

I claim:

1. An electrode, suitable for carrying out electrochemical reactions inan electrolysis cell adapted to contain a level of electrolyte therein,comprising:

an electrode element comprising a generally solid section ofelectrically conductive material;

an electrically conductive current collector mounted in said electrodeelement; and

at least one passageway means formed in and extending through saidelectrode element in a generally vertical direction for permittingelectrolyte to enter said electrode element from said cell, circulatetherethrough, and exit from said electrode element to said cell.

2. An electrode structure according to claim 1 wherein said electrodeelement comprises porous carbon, a downwardly open cavity is formed inthe lower portion of said electrode element, and a hollow conduit meansis secured to the lower end of and extends said passageway through saidcavity.

3. An electrode structure according to claim 1 wherein: said electrodeelement comprises an inner essentially impervious core section and anouter porous section secured to said inner core section; said currentcollector is mounted in said core section; and said passageway extendsthrough said core section.

4. An electrode structure according to claim 3- wherein: said outersection comprises a porous carbon and is generally rectangular in shape;said core section comprises a dense essentially impervious carbon and isgenerally rectangular in shape; said outer section is disposed on oneside of said core section; a generally rectangular second outer sectioncomprising a porous carbon is disposed on the side of said core sectionwhich is opposite said first-mentioned outer section; and a fasteningmeans is provided for securing said core section and said outer sectionstogether.

5. An electrode structure according to claim 3 wherein: said outersection comprises a porous carbon, is generally cylindrical in shape,and is hollow; and said core section comprises a dense essentiallyimpervious carbon, has the general shape of a generally cylindrical rod,and is disposed within said outer section.

6. An electrode structure according to claim 5 wherein: said outersection extends at one end thereof beyond one end of said core section;the bottom surface of said core section together with the inner surfaceof said extended portion of said outer section define a cavity in thelower portion of the electrode; and a hollow conduit means is secured tothe lower end of and extends said passageway through said cavity.

7. An electrode structure according to claim 4 wherein said currentcollector comprises a hollow conduit and extends through said coresection into communication with said cavity.

8. Electrochemical conversion apparatus comprising, in combination:

an electrolytic cell for containing a level of electrolyte;

an electrode structure in accordance With claim 5 adapted to be disposedin said electrolyte; and

means for introducing an inert gas into said hollow conduit means.

9. Electrochemical conversion apparatus in accordance with claim 8,comprising in further combination:

a product separation means for separating hydrogen or other inert gasfrom a product efiluent stream from said cell;

a product effluent conduit connected to said cell and to said productseparation means; and

a second conduit means connected to said separation means and incommunication with said hollow conduit means for introducing at least aportion of said hydrogen or other inert gas into said passageway.

10. Electrochemical conversion apparatus in accordance with claim 9,comprising in further combination:

a temperature sensing means disposed in said electrode structure formeasuring the temperature within said electrode;

flow control means disposed in said second conduit means; and

temperature controller means operatively connected to said temperaturesensing means and said flow control means for adjusting said flowcontrol means and controlling the flow of said hydrogen or other inertgas to said hollow conduit means and said passageway responsive to saidtemperature measurement.

11. Electrochemical conversion apparatus comprising, in combination: anelectrolytic cell for containing a body of electrolyte; an electrodestructure in accordance with claim 1 adapted to be disposed in saidelectrolyte; and

9 means for introducing an inert gas into said passageway which extendsthrough said electrode structure.

12. Electrochemical conversion apparatus in accordance with claim 11,comprising in further combination: a product separation means forseparating hydrogen or other inert gas from a product effluent streamfrom said cell; a product efiiuent conduit connected to said cell and tosaid product separation means; and a conduit means connected to saidseparation means and in communication with said passageway forintroducing at least a portion of said hydrogen or other inert gas intosaid passageway.

13. Electrochemical conversion apparatus in accordance with claim 12comprising in further combination: a temperature sensing means disposedin said electrode structure for measuring the temperature within saidelectrode; flow control means disposed in said conduit means; andtemperature controller means operatively connected to said temperaturesensing means and said flow control UNITED STATES PATENTS 3,655,5354/1972 Ruehlen et a1. 204294 3,076,754 2/1963 Evans 204274 2,706,1754/1955 Licharz 204-274 1,365,032 1/1921 Greenwalt 204-277 1,249,78712/1917 Leuchter 204277 JOHN H. MACK, Primary Examiner W. I. SOLOMON,Assistant Examiner US. Cl. X.R.

UMTED STATES .PA'EEN'E OFFICE (I'ER'HMQA'EE 0F CGRMEQ'REUN Patent: No.772 Z01 Dated November 13, 1973 lnventofls) king L. M1115 It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 8, claim 7, line 36, "claim 4" should read claim 6 Signed andsealed this 9th day of April 1974.

(SEAL) Attest:

. EDWARD M.FLETCHER,JR. C. MARSHALL DANN Attesting Officer Commissionerof Patelfts FORM PO-105O (10-69) USCQMM'DC 60376-P69 .5. GOVERNMENTPRINTING OFFICE: I969 0-366-334.

